Apparatus for the continuous drainage of wet sand



Sept. 29, 19 59 D. BLANKEVOORT ,4

APPARATUS FOR THE CONTINUOUS DRAINAGE 0F WET SAND 2 Sheets-Sheet 1 Filed Sept. 12. 1955 ATTORNEY Sept; 29, 1959 D. BLANKEVOORT 2,

APPARATUS FOR THE CONTINUOUS DRAINAGE OF WET SAND Filed Sept. 12, 1955 2 Sheets-Sheet 2 INVENTOR Di l-[f B Zen/(e vea -Z ATTORNEYS APPARATUS FOR THE CONTINUOUS DRAINAGE OF WET SAND Dirk Blankevoort, Bloemendaal, Netherlands, assignor to D. Blankevoort & Zoon N.V., Bloemendaal, Netherlands, a Dutch limited corporation Application September 12, 1955, Serial No. 533,549

8 Claims. (Cl. 210-400) The invention relates to an apparatus for the continuous drainage of wet sand, and similar material, and to a method for draining wet sand.

A method is already known for draining wet sand dumped in sandor dredge-prams, the prams being provided with a double bottom, whereby the water collects in the space between the two bottoms, from which it is removed by suction. g'

This known method can only be used when the said pram is provided with the special double-bottom, and ordinary prams therefore can not be employed. If a normal pram is to be used for transporting dry sand, the sand must first be drained in a double-bottomed pram, and subsequently be transferred into a normal pram. This involves transfer cost and loss of time.

The invention provides an apparatus in which these disadvantages have been removed, and which will drain sand or similar material by a continuous method. The apparatus of the invention is characterized in that it is. provided with a hopper with an outlet, a mechanically driven conveyor mounted beneath the hopper, and a stationary filter member connected to means for applying suction. The conveyor may be constituted by an endless belt of channel section at the top, while the filter member may consist of at least one perforated tube of any shape or section, which may extend over the whole length of the conveying surface.

The apparatus of the invention is further characterized Patented Sept. 29, 1959' suction-pump, with the container provided with controls for regulating the dater level and the degree of vacuum.-

The method for the continuous drainage of wet sandor similar material is characterized in that a stream of wet sand issues from a hopper onto a continuously running, mechanically driven conveyor fitted with a stationary filter'member, by which during the transport of the wet material liquid is continuously drained by suction.

A characteristic feature of the invention is the method for draining liquid from wet sand and similar material, whereby liquid is first drained from the material in hydrocyclones, and subsequently in an apparatus of the invention.

In hydrocyclones, liquid may be drained from a sandsuspension down to a water-content of percent. When the wet sand is subsequently drained by suction in a draining apparatus of the invention while being transported by a conveyor, the water-content can, in between 20 and 40 seconds, be reduced to 8-10 percent.

When with the method and apparatus of the invention, a conveyor is used, it is necessary that, while transporting the sand or similar material, in particular when the sand still contains a great deal of moisture, the edges of r the belt are raised. This is impossible with a normal conveyor, which is stiffened with canvas, and is consequently of moderate flexibility. In the apparatus of the invention this drawback has been removed by employing a highly flexible conveyor consisting of a relatively stiff,

' middle-strip, and very flexible side-strips made of elastic by the fact that the filter member consists of at least one set of inner and outer perforated tubes, and on the inside is covered with a fine-meshed gauze, thespace between the tubes being filled with a layer of cotton-wool, or slag wool, or some pulverulent material, such as sand, of a grain size larger than the mesh of the gauze. With this kind of filter member the vacuum in the inner tube does not suddenly disappear, if during draining clefts should occur in the mass in the filter member.

The best method is to use the inner tube as a filter member proper; the perforations in the outer tube may then be coarser. This makes it unnecessary to minimize Wear and tear of the outer tube by the constant passage of the sand; which may take the form of a rubberized tube. Wear and tear of the filter member proper is then practically excluded.

According to another object of the invention the conveyor may take the form of a rotatable worm in a hollow container, the container having a porous bottom which constitutes the filter member, and being closed at the bottom. The hollow space thus formed is connected to material reinforced with bars. The strips are joined by a pliable connection; and guides or rollers place the sides of the conveyor in an upright or slanting position as required. Though consisting of highly flexible material, the reinforcing bars make the side-strips very stiff, so that, when standing up between successive sets of guides, they do not collapse onto the material of the conveyor.

The drawing shows diagrammatically a form of apparatus for the continuous drainage of wet material, such as sand, constructed in accordance with the invention; in which 1 Figure 1 is a schematic side view of an apparatus, in which the conveyor consists of an endless belt;

Figure 2 is a cross-section of Figure 1 takenon the line 2-2 of Fig. 1;

Figure 3 is a cross-section of an apparatus constructed in accordance with the invention, in which a conveyor is used, the sides of which can be raised;

Figure 4 is a partial side View of the apparatus constructed in accordance with Figure 3 and taken on line 4-4 of Fig. 3;

Figure 5 is a side view of the conveyor referred to in Figures 3 and 4;

Figure 6 is a cross section of a detail of the conveyor; and

Figure 7 is a cross section of the drain tube.

The apparatus of Figures 1 and 2 comprises a hopper or supply-bunker 1, in which the Wet sand 2 to be drained, is dumped. The wet sand falls through the outlet of the hopper onto the endless belt 8 of the conveyor 5, the conveyor being guided over rollers 6 and 7, one of which at least is mechanically driven or rotated.

As shown in Fig. 2 the sand 9 to be drained passes. during transport through the hollow channel of the belt, supported by guides 11 (which may be rollers).

In the middle of the sand 9 (Fig. 2) is a porous drain-- ing tube 10, in which a vacuum is created so that thesuperfluous water is drawn from the passing wet sand bysuction.

The draining tube 10 is connected to a container 12,. in which the extracted mixture of air and water is separated into sections 13 and 14. An air pump 16 sucks. oil the air through tube 15, the water being drained by' suction through tube 17 by a water pump 18. The container 12 is further provided with means for controlling the level of the water therein,- and the degree of vacuum.

The draining system of the apparatus thus automatically adapts itself during operation to the proportion of the quantities of air and water that are removed.

Practice has taught the necessity of preventing the wet sand 2 issuing from the hopper 1, and the material 9 on the conveyor from forming a homogeneous mass; other; wise the wet material in the hopper is drained to such an extent as to stop a regular flow of the material. For a regular flow of sand from the hopper it is necessary that the sand retains a sufficient amount of moisture. To this end the apparatus of the invention is fitted with an interrupter 3 between the hopper 1 and the conveyor 5. This interrupter brakes the flow of wet sand 4 from the hopper 1. In the drawing of the apparatus constructedin accordance with the invention this interrupter has the form of a rotating blade-wheel. The weight of the material falling on the blades rotates the wheel, which may also be mechanically driven.

In the apparatus shown in Fig. 3 the filter member consists of an inner tube 23, and an outer tube 24, which are perforated, and on the inner side covered with a finemesh gauze, the space between the perforated tubes being filled with a layer 25 of filter material such as cotton wool, slag wool or pulverulent material, such as sand, of a grain size larger than the mesh of the gauze.

The conveyor of the apparatus shown in Figs. 3 and 4 consists of a middle strip 26 made of a comparatively stiff material, and the sidestrips 27, made of flexible material, which are joined to the middle-strip by means of the pliable connection 28.

Fig. 6 shows a form of construction of the connection 28 between the middle-strip 26 and the side-strip 27. The pliable connection 28 is by preference vulcanized to the middle strip 26 and the side-strip 27. The side-strips 27 are reinforced with bars 29, which may take the form of fiat steel springs.

The conveyor is driven by the roller 6, while the surface is supported by the guides (or rollers) 30.

The side-strips 27 are kept in a raised position by the guides (rollers) 31 during the transport of the material 9 as long as it is very wet.

It is evident that the apparatuses. described above for applying the method of the invention are merely forms of construction; they are open for numerous constructive modifications without trespassing beyond the scope of the invention.

I claim as my invention:

1. Apparatus for the continuous drainage of liquid from wet materials such as sand, comprising a continuously movable belt conveyor, a pair of spaced rollers around which the conveyor moves, means mounted near one end of the conveyor and above the latter to feed the material onto the belt, a perforated tube arranged along substantially the entire length of the belt, and means connected to the tube to apply a vacuum to the tube to extract the moisture from the material as the latter is conveyed along the belt in contact with the tube.

2. Apparatus according to claim 1, in which the firstmentioned means is in the form of a hopper for receiving the material to be drained of liquid to be fed onto the belt.

3. Apparatus according to claim 1, in which the lastmentioned means includes a container having an air pump connected thereto to create a suction in the tube.

4. Apparatus according to claim 1, in which the lastmentioned means includes a container having an air pump connected thereto to create a suction in the tube and a liquid pump connected to the container to remove the liquid withdrawn from-the material.

5. Apparatus according to claim 1, in which a plurality of guide rollers are provided for the bottom and side sections of the belt to support the latter and impart a channel configuration to the belt.

6. Apparatus for the continuous drainage of liquid from wet pulverulent material such as sand, comprising ahopper for the reception of the wet material, a continuously movable conveyor mounted beneath the hopper, a stationary filter member associated with the conveyor and means for applying suction to saidfilter member, the conveyor comprising an endless belt of channel'section and the filter member including a perforated tube arranged in the channel and extending over substantially the entire length of the conveyor.

7. Apparatus according to claim 6, in which the filter member comprises inner and outer coaxial perforated tubes having their inner Walls covered with gauze of a mesh finer than the grain size of the material to be drained, the annular space between said tubes containing a filtering medium of grain size larger than the mesh of the gauze.

8. Apparatus for the continuous drainage of wet sand comprising a mechanically driven conveyor, a hopper over the conveyor, a stationary suction member mounted substantially over the entire length of the transporting surface, the suction member being a porous tube provided with an inner and outer perforated tube, the inside wall of at least the inner tube being covered with gauze with fine mesh, and the space between the tubes being filled with a filtering material of a grain size larger than the mesh of the gauze.

References Cited in the file of this patent UNITED STATES PATENTS 2,676,469 Wenzelberger Apr. 27, 1954 2,686,192 Bonotto Aug. 10, 1954 FOREIGN PATENTS 880,582 France Jan. 4, 1943 868,588 Germany Feb. 26, 1953 w n... g,- 

